Nociception is the physiological sense that signals the brain about damaged nerves or tissue. Felicia's nociceptors, or pain sensory receptors, respond to the damaging stimulus of the hammer on her thumb by sending information to the spinal cord and brain, making her feel physical pain, thus allowing her to react to the situation in an appropriate manner. Even though her pain receptors are usually silent (or dormant), they react instantaneously to the damage.
